Few words about the releases.

Galera 2.7 and wsrep patch for MySQL 5.5.33 are straightforward maintenance releases, with plenty of bugs fixed and one new feature (support for multiple SST donors list). Upgrade is warmly recommended.

Galera 3.0 and wsrep patch for MySQL 5.6.13 are the first beta releases of what shall become our main product line in the future.

New in Galera 3.0:

new writeset format optimized for performance and reduced memory usage.

128-bit writeset checksums, checked every time before writeset is applied, so that corruption cannot sneak in neither on disk, nor in transfer.

ability to divide cluster into segments with minimized communication between them to minimize network traffic over WAN. Parameter: gmcast.segment.

wsrep patch for MySQL 5.6.13 is the first wsrep release in MySQL 5.6 line, which includes support for MySQL GTIDs, both preserving remote master GTIDs and generating consistent GTIDs for local Galera events on all nodes for easy slave failover.

Upgrading existing installations:

Note that Galera 3.0 and wsrep patch for 5.6.13 are considered BETA quality, so production system upgrade is not recommended yet.

Since they introduce a number of new configuration variables rolling upgrade will need to take 2 rounds: 1st round - software upgrade with old configuration. 2nd round - configuration upgrade where new options can be utilized. For compatibility with 2.x all 3.x nodes must have "socket.checksum=1" in wsrep provider options.

As usual, Galera and mysqld binaries supporting the same wsrep API (23 or 24) are mutually compatible and can be combined arbitrarily.